I remember when MS was developing Cassini - I believe they rolled it into VS 05/08, so I think this is a Cassini web server question.
I am using Windows XP with Vi
Microsoft doesn't allow this on purpose - they don't want you deploying your application with Cassini. It's compiled right into its code.
That being said, I've often wondered if they just check the url for "localhost". Perhaps editing the HOSTS file of the remote machine and redirecting "localhost" to the cassini machine could trick it? Worth a shot... In windows you can find HOSTS here:
C:\Windows\system32\drivers\etc
You can go into your web project settings and have it use the local IIS as a host instead, and then it will work fine.